It is common in fluid piping systems, such as municipal, industrial, and institutional water supply systems, for there to be extended runs of fluid piping between valves. As a result, it has been necessary to shut down extensive segments of the piping system in order to perform repairs or other work in a small section of the system. The interruption of fluid flow through the system or extensive parts of the system is usually inconvenient at the least, and may have serious economic or safety ramifications. In some situations, such as water supply systems to hospitals, shut down for even a brief period is impracticable.
Several different approaches to placement of valves in piping systems without interruption of fluid flow through the system have been attempted and are known in the prior art, but none of the known approaches has provided a fully coordinated and fully effective solution of the problem. One approach is illustrated by U.S. Pat. No. 3,633,598 to Morris, et. al., which discloses an apparatus and method for inserting a spade valve between the flanges of a joint in a fluid line. While perhaps of significant benefit in association with a piping system characterized by flanged joints, when such a flanged joint occurs in a location where insertion of a valve is required, this approach is, by its nature, limited, and of no benefit in a system in which pipe sections are joined by means other than flanges.
Another approach consists essentially of cutting a slot-like opening partially or wholly through the pipe, in a plane perpendicular to the longitudinal axis of the pipe, and inserting a spade-type valve member into or through the slot. Interruption of fluid flow is achieved by sealing of the faces of the spade valve member against the edges of the slot or ends of the fully severed pipe. Various embodiments of this basic approach are illustrated by U.S. Pat. No. 3,703,906 to Tickett, U.S. Pat. No. 3,749,108 to Long, and U.S. Pat. No. 3,785,041 to Smith. This approach may present difficulties in achieving a positive seal of the valve member against the ends of the pipe at the point of severance, and full severance of the pipe is undesirable in many situations, in that it results in a break in the integrity of the pipe. Further, in many instances, the means of cutting the slot are integral with the valving apparatus and remain in place after installation of the valve, increasing the complexity and cost of the apparatus used in the practice of this approach.
Yet another approach is generally characterized by cutting a circular hole through the wall of the pipe, with the hole centered on an axis perpendicular to the longitudinal axis of the pipe, and insertion of a generally cylindrical plug valve member into the interior of the pipe through the hole. Pressure is then imposed against the top of the plug valve member, which is typically constructed of an expandable material such as rubber, in order to cause the plug valve member to expand to fill and block the interior of the pipe. This approach is illustrated by U.S. Pat. No. 3,799,182 to Long, U.S. Pat. No. 3,948,282 to Yano, and U.S. Pat. No. 4,552,170 to Margrave. While this approach is effective in many situations, it does not address certain problems inherent in many fluid distribution systems. In order to achieve a complete seal between the expandable valve member and the inside surface of the pipe in which the valve is to be installed there must be full contact between the surface of the valve member and the inner surface of the pipe. If the pipe has been in service for any period of time, especially in a water distribution system, the inner surface of the pipe will typically be corroded and/or contain mineral deposits, so that the pipe surface is rough and irregular and a secure seal against that surface is difficult to achieve. The rough inner pipe surface and the rough edges of the hole cut into the wall of the pipe for installation of the plug valve member generally cause damage to the plug valve member when it is forced tightly against those surfaces and edges, and the number of opening-closing repetitions which may be performed before failure of the plug valve member is limited. In addition, because of the close dimensional tolerances required, a different plug valve member must be produced for each different pipe wall thickness, even within the same nominal pipe diameter, increasing the cost of both manufacture and inventory maintenance.
Therefore, there remains a need in the industry for an inline fluid flow control valve, as well as apparatus for and method of installation of such a valve, which enables a user to effectively install such a valve in a fluid line, under pressure, without interrupting the flow of fluid through the line, and without encountering the disadvantages that have not been addressed by the prior art. It is, accordingly, among the objects of the present invention to provide a valve apparatus which achieves a positive closure of the fluid line without damage to the valve member, which is useable in a single size with a variety of fluid line wall thicknesses within the same nominal line size, and which may be effectively operated through a large number of opening-closing repetitions without failure. It is further among the objects of the present invention to provide an apparatus for installation of the valve of the invention, and a method of installation of the valve of the invention utilizing the installation apparatus of the invention.